Thread cutting mechanism



y 12, 1932- E. B. ALLEN THREAD CUTTING MECHANISM Filed March 3, 1928 4 Sheets-Sheet 1 INVENTOR Edward B. A lien TTORN EY WITNES ES y 1932- E. B. ALLEN THREAD CUTTING MECHANISM Filed March 3, 1928 4 Sheets-Sheet 2 INVENTOR PK Ewan! 514/19 ATTORNEY July 12, 1932.

E. B. ALLEN THREAD CUTTING MECHANISM Filed March 3. 1928 4 Sheets-Sheet 5 A llll' A INVENTOR Efzward EAZlera WITNESSES BY l ATTORNEY w QM 4 Sheets-Sheet 4 INVENTOR fiUzz/ard [IA/[em E. B. ALLEN THREAD CUTTING MECHANI SM Filed March 3, 1928 July 12, 1932.

TTORNEY Y B |ll.l m I. m. I NR Nw NW w a H W QW M WW gg- NM km s S N w W Patented July 12, 1932 EDWARD iB. ALLEN, I TE WTDWZDT, CONNECTICUT, ASSIGN OE TO SINGER -MANU- FACTUBIIIG COIIHE'AITY, OF ELTZABETH,

- JERSEY NEW o'ERsEY, 3A oonronnrron --'.ITIEER]-]AID GUT-TING- MEGHANISM Application filed March s,

This invention relates to; thread-cutting mechanism for sewing machines, moreparticul-arly of the buttonhole type, and has for an object toimprove the thread cutting mechanism disclosed in the patents to Allen No. 1,579,200, of April a, 1:926, and No. 1,600,206, of September- 21, 1926, to'secure a uniformly high degree of certainty of operation of the mechanism in sewing operations on all of the various classes ofmaterial'mct with in practice. Buttonhole sewing machines are commonly called upon to sew buttonholes in fa rics of widely different physicalcharacteristics, some of such fabrics being'knitted and others being woven; both knitted and woven fabrics varying greatly in thickness, weight, texturepetc. A v p In my prior thread-cutting mechanism there embodied a scissors thread-cutter, the blades of which'are disposed transverse to the plane of the work- "Sucl thread-cutter is carried by a swinging lever which moves it arcuate path causing one of theblades to graze the under surface of-thej' work and pass between the latter and the sewing tit-reads and cord which lie parallel to and in contact with the under surfaceof-the work from the last stitch to the needle-throat memher, from which they aredrawn out by the movement of the work-clamp from sewing position to butto'nhole cutting-positionat the end of the sewing period. i

The settingor adjustment ofthe operative radius of such thrcad-cutter'is rather-critical as, if too short, the upper scissors point is not likely to catch all of the threads and cord and, if too long, there is danger that the scissors point will snag the ;work,'particularly if the latter is of a soft or spongy nature allowing-the threads to sink-into the fabric.

According to the present improvement, provision is made'for relatively separating the worl; and threads-to be cut, to provide a space for entr'yof the thread-cutter or scissors point, thus materially broadeningthe rangeof a1- lowable variation in. the adjustment and maintenance oft-he operative path Cir-radius of the thread-cutter, for successful operation.

While various specificmechanismsmay oh- 1928. 'Seria11q'o.-258,772.

viously be provided for relatively se arating the work and threads to be "cut, it'is'fpreferred to accomplishthe result by li ftin anu holding'lifted the front end of the wink clamp, and such lifting may be'conveni'e'ritly effected by a cam'iixed to thethre'a'd-cutt'er carrying lever. V

In the accompanying drawingsFig. '1 "is a side elevation of a buttonholesew ing machine embodying the invention. Fig. 2 isa front end elevation or the'machine. F igl? is a rear view andFig. an-endview of the work-Clamp liftingcam and associated parts. Fig.5; is a plan'view ofthe parts'below the work-clamp ofthe machine. 'Fig. Bis a-Section on thecline 6-6,Fig. 1., f Fig.f7 is a sec t-ion on-the-line 77,Fig..6. Fig.8 i's-avside elevation of the work-clamp and thre'adcutter inthread-cuttingposition. Fig. "9 is'j'a perspective view of the clamp li-fti'ng cam follower, and FigQflO is a' transverse sectional view through the work-clamp showing the thread-cutter in cutting'position. I

'In' the preferred embodiment of thei nve'ntion'illustrated, '1 represents the bed, "2 the standard, 3 the overhanging arm and'Zl the head of a buttonhole sewing machine ofith'e type discl'osed in the patent'toA'llen No. 15,824yreissued April 4:, 1922. The "stitch- -forming-mechanism is constructed substantially in accordance with the -di c1osure the Allen et "a1. Patent No. 1,372,473,f(if March 22, 11921,and comprisesthe reciproeating and laterally vibrating needle '5 and the usual underthread mechanism mounted on the rotary turret 6 and including the threaded'looper 7, non-threaded looper sand loop-det'ainers 9 and 1 0. The turret ?6,,also carries thejneedle-throat member l1 whichlis formed with the usual needle-aperture 1'2, and guideway-for-the stay-cord c. 'Itheperiodof operation of the stitch-forming mechanism is cont'rolled bythe usual stop-motion device l3'by which -the flow of power ffromthecontinuously ru-nning belt-pulley 114 to the sewing} shaft -15'is established and interrupted.

- The buttonhole cutting-mechanism is con- .s'tructedsubstantially in accordance with the disclosure of my said reissued patent .and

comprises the upper and lower cutterf levers noted, is of the usual construction disclosed in sa d reissued patent.

It comprises the lower worlysupporting plates 24 and upper clamping feet 25 carried by the clamp-arms around the buttonhole.

, 26 fulcrumed at 27 on theblocks 28 mounted on the plates 24. The clamp-plates 24 are.

carried by the usual cross-slide-plate 29 which, in turn, is carried by the usual longitudinal slide-frame 30. The cross -slide-plate 29 andflongitudinal slide-frame 30 have the usual operative connections with the feed i wheel 31, which is given a step-bystep feed ing movement through the usual connections with the sewing shaft 15, to place the stitches It is also given a i 'l rapid continuous movement, both prior and subsequent to sewing, by the rapid-feed shaft 32 through the gear-connection 33 with the cross-sha t v34 operated at the proper times by a clutch-connection, not shown, with the gear35 driven continuously by the worm 36 on therapid-feed shaft 32, During the rap id continuous movement of the feed-wheel 31, the work-clamp is shifted forwardly,,transversely of the needle-path from buttonholecutting positiomFig. 8, to stitching position, and, when the sewing is completed,'is rapidly returned to buttonhole-cutting position.

It is well known that the needle-throat member of a machine of the type under consideration supports the portion of the work immediately adjacent the sewingpoint and is adapted to guide a stay-cord to the stitch forming mechanism,so that the stitches will be formed over the stay-cord and bind the latter in position around the buttonhole. Also, it is known that when the stitch-forming mechanism of amachine of the type under consideration is stopped, a loop of needlethread is retained by theloop-taker mechanism'. Consequently, when the work is shiftedrearwardly from sewing tocutting position, there are four thread-lengths leading from the needle-throat member to the last stitch. One of these threads is the stay-cord- Another is the under-or looper-thread. The

remaining two are the limbs of the detained needle-loop. These threads lie substantially parallel to and in contact with the under surface of the work.

' The work-clamp is closed by a rocking movement of the connected rock-shaft sections 38 one of which has fixed thereto the rearwardly extending arm 39 which is depressed by the automatically operated lever 40, the action of which is described in said reissued patent. The rock-shaft sections 38 may be manually operated to close the workclamp by rearwardmotion of the usual upwardly extending finger-piece 39 fixed to the: same rock-shaft section 38 which carries the rearwardly extending arm 39. The clampclosing means may thus be either manually or automatically operated.

The thread-cutter is constructed substantially in accordance with the disclosure of the patent to Allen No. 1,579,200 of April 6, 1926.

It comprises a scissors device having anupper' pointed blade 41 fixed to and carried by the thread-cutter lever 42 which is fulcrumed at 43 to the machine frame." Pivoted at 44 to the upper scissors-blade'41 is the lower scissorsblade 45 the tail of which has a lateral pro;

jection 46 entering the-scissorsclosing camslot 47 in the stationary cam-plate 48. This scissors device i disposed in a vertical plane transverse to and intersecting the lead of the threads and cord extending from the needle-throat member to the stitched buttonat 51-to the framesbra'cket 52 and having a -follower 53 entering the thread-cutter camgroove 54 in the gear 33, as disclosed in the patent toAllen l loi 1,600,206, of September 7 In my prior constructions the scissors device was preferably adjusted to an operative radius such that the upper pointed blade grazed the under surface of the work and entered between the latter'and thetlireads to be cut. According to the presentimprovement, means are provided for relatively separating the under surface ofthe work and the threads and cord, to provide a space for entry of the upper scissors-blade, thus materially broadening the range of allowable variation in the adjustment and maintenance of the operative path or radius of the threadcutter. The separation of the work and threads to be cut is preferably effected'by relatively moving the work-clamp and needle-throat member vertically. In the present effected by means carried by the thread-cutt-er lever 42 and adapted to elevate the front end of the work-clamp during the advance of the thread-cutter to operative position.

The lower clamp-plates 24 have at their rearward lends the usual laterally slidable connection 55 with the under-cut forward edge of'the retainer-plate 56 fixed to the crossslide-plate 29, as disclosed'insaid reissued patent. This connection is free enough to permit of the upward tilting of the workclamp sections about such connection as a center. Connected to sockets in the front ends ofthe. workclamp sections are the ballshaped upperends 57 of pins 58 which are. received in the tubes 59 fixed to the plate 60 carrying the cam-follower roll 61. The pins 58 are grooved at 62' for reception of the circular portion'63of the latch-lever '64 which is fulcrumed at 65 to the plate 60. The circular portion 6230f the latchdever is formed at diametrically opposed poi nts with recesses 66 which, when shifted into register with the pins 58, perm-it upward removal of suchpins from the tubes 59 in removing theclamp sections from the machine. The spring 67 biases the latch-lever (id to locking position, Fig. 7 The tubes 59 are slidably received in holes 68in the block 69 secured to the cross-slideplate 52-9. The spring 70 yieldingly retains the clamp-plates 24=upon the cross-slide-plate 29. The stop 69 limits the downward motion of the plate 60 under the influence of the spring 70 when the pins 58 are released. Screwed into thethread-cutter lever 42 are the stud-pins 71 to the outer ends of which is fixed the cam-plate- 7 2 having a portion 73 concentric with the pivotal center 43 of the lever 42 and a portion Hextending nearer thecenter43 from the portion 73.

When the work-clamp is shifted to buttonhole cutting position, Fi g. 8, the follower roll 61 lies directly over the cam plate 7 2 so that, as the thread-cutter lever 42 is operated to advance the-tliread-cutter, the pins 58 are lifted, thus tilting the work-clamp upwardly and raising the stitched workrelative to the needle-throat member 11, as'shown in Fig. 8. This action separates the under surface of the work from the'threads extending from the last stitch to the needle-throat member, and causes such threads to extend at an angle to "the under surface of the work, the space within such angle being ample to receive the pointed upper blade of the thread-cutter which need not be set or adjusted as finely as would be necessary were no preliminary separation of the work and threads, provided for. The point 41' of the upper scissorsblade'is preferably offset or curved forwardly toward the needle-throat member from the thread-cutting plane,w"-y,' to take advantage "of the increased space provided forentry of such pointbetween the work and the threads, at thcincreased' distance from the apex of the angle formed by the under surface of the work and'threads to be cut.

The thread-cutter carries a'nipper 7 5 for seizing the severed needle-threadloop 7 6 and removing'it from thestitch-forming mechanism. This nipper is constructed substantially in accordance with the disclosure of said Patent- 'No. "1,579,200.

Having thus set forth the nature pit the invention, whatl claim herein is:

l. Ina sewingmachine in which the thread to be .cut extends from thelast Stitch to the needle-throat member substantially incontact withlthe under surface of thework, .a

thread-cutter including an element normally 7 occupying a retracted position, means for relatively separating the work andthreadsto be cut to provide aspace for entrywo-f the thread-cutter element, and meansfor proj ectingthe-thread-eutter element into such space.

:2: A. sewing machine including stitchformingmechanism, aneedlethroat member, a work-clamp, means for relatively feeding the stitch forming mechanism and workclamp to sew a group of stitches and for relatively shifting the stitchdormingmechanism and work-clamp afterthe sewinggis completed to laterally space the group of stitches from the needle-throat member, a threadecutterineluding a pointed blade. disposed transverse to the planeofthework an-dbelow the workclamp, means for relatively separating the work and thethreadsleading from theneedlethroat member'to the group of stitches-to provide a space for entryofithe thread-cutter blade, and-means foriprojectingqthe point: of the threadcutter sblade into such space to s-everthe threads. y

3. In a sewing machinein'which that portion of the thread to;begoutilies substantially in contact-with the surface :of the work, .a thread-cutter including a blade. disposed transverse to the surface of the workand having a pointed extremity, means for relatively separating the :work and thatportion of the thread to'be cutjtoprovlide aspace for entry of the pointiof th e thread-cutter blade, and means for iprojectingthe thread-cutter blade into such space'to cutthe thread.

4; in asewing machine inwhich-that portion of the thread to becut lies substantially in contact with the surfaceof the work, a

threadcutt-er including a :blade having-1a pointed extremity, said. thread-cutter being pivotally mounted so as to direct the {IIlOVG- ment of the pointed extremity of the. blade in a curved path crosswiseof the lead ofthe thread, and means :for relatively separating the work and thread to *be out to provide a space for'entry of the point 'of thewthreadcutter blade. s

5. In a sewingcmachine, ;stitch-forming "mechanism, a'needle throatmember, a'workclamp, clamp-closing means, means for relatively feedingthe stitch-forming mechanism and work-clamp Jto sew ca :group of st-itehes,

means for relatively separating "the -workclamp and needle-throat membertrans'versly of the plane of the work :While=:the w0rkclamp :remains closed upon'the work,;and

means 'for severingrthe :thread while the needle-throat member and workeclarnp glg j rlativly separated.

6. In a sewing machine, stitchforming mechanism, a. needle-throat member, a workclamp, clamp-closing means, means forrelatively feeding the stitch-forming mechanism and work-clamp to sew a group of stitches and for relatively separating the stitch-forming mechanism and work-clamp transversely of the needle-path after the sewing is completed, means for relatively separating the work-clamp and needle-throat member transversely of the plane ofthe work, while the work-clamp is closed upon the work, and means for severing the thread below the work while theneedle-t'hroat member and workclamp'are relatively separated V V 7. In a sewing machine, stitch-forming mechanism, aneedle-throat member, a workclamp, clamp-closing means,means forrelatively feeding the stitch-forming mechanism and work-"clamp'to sew a group of stitches and for relatively separating the stitch-forming mechanism and work-clamp transversely of the needle-pathafter the sewing iscompleted, means for lifting the work-clamp while the latter remains closed upon the work, and means for severing the thread while the work-clamp is lifted.

8; In a sewing machine, stitch-forming mechanism, a needle-throatmember, a workclamp, means for relatively. feeding the stitch-forming mechanism and work-clamp to sew a group of stitche'sand for relatively separating the stitch-forming mechanism and work-clamp transversely of the needle-path after the sewing is completed, means for lifting' one end of the work-clamp to tilt the latter upwardly, and means for severing the thread while the work-clamp is tilted.

9.- In a sewing machine, stitch-forming mechanism, a needle-throat member, a work clamp, clamp-closing means, means .for relatively feeding the stitch-forming mechamsm and work-clamp to sew a group of stitches and forrelatively separating the stitch-forming mechanism and work-clamp transversely of the needle-pathafter the sewing is completed, thread-cutting mechanism below the work-clamp, and means operated by the thread-cutting mechanism for relatively sep- -arating the work-clamp and needle-throat member vertically while the work-clamp remains closed'upon the work.

10.-In a sewing machine, stitch forming mechanism, a needle-throat member, a workcla'mp, means for relativelyfeedingj the s'titcl1-forming mechanism and work-clamp to sew a group of stitches and for relatively separating the stitch-forming mechanism and "work-clamp transversely of the needle-path after the sewing is completed, thread-cutting mechanism including a thread-cutter lever mounted belowthe work-clamp, and means connected to be operated by said lever for lifting the front end ofthe work-clamp.

11. In a sewing machine, stitch-forming mechanism, a needle-throat member, a workclamp, means for relatively feeding the stitch-forming mechanism and work-clamp to sew a group of stitches and for relatively separating the stitch-forming mechanism and work-clamp transversely-of the needle.- path after the sewing is completed, thread cutting mechanism including a threadcutter type, in combination, stitch-formingmechanism, a needle-throat member, a work-clamp, a buttonhole cutter, means for relatively movin g the stitch-forming mechanism and works clamp to sew around a buttonhole, means for moving the work-clamp from stitching position to buttonhole cutting position removed from stitching position, thereby drawing out thread and cord from theneedle-throat member, which thread and cord lie substantially in contact with the under side of the work,

a threadand cord-cutter, and means for 'rela-, tively separating the work from said thread and cord to provide a space for entry of said threadand cord-cutter.

14. In a sewing machine ofthe'buttonhole type, in combination, stitch 'forming mechanlsm, a needle-throat member, a worn-clamp, a buttonhole cutter, means for relatively moving-the stitch-forming me'chanismnand work clamp to sew around abuttonhole, meansfor moving the work-clamp from stitching position to buttonhole cutting position removed from stitching position,thereby drawingout thread and cord from the needle-throat member, which thread and cordlie substantially in contact with the under side of the work,

a threadand'cord-cutter, and means for relativelyseparating the work-clamp and needlethroat member transversely of the plane of the work to separate the thread and cord from the under surface ofthe work and provide a spacefor entry of the thread-and cord-cutter.

. 15. In a sewing machine, a .work-clamp,

clamp-closing means, a thread-cutter, and 7 means for lifting the closed work-clamp and for operating the thread-cutter while the workclamp is lifted. i

16. In a sewing machine, a needle, aneedle-,

throat member, a work-clamp, clamp-closing means, a thread-cutter, and. means for relatively separating'the closed work-clamp and needle-throat member transversely of the plane of the work and for. operating the thread-cutter while the work-clamp and needle-throat member are relatively separated.

17. In a buttonhole sewing machine, stitchforming mechanism, a work-clamp, a button hole cutter adapted to cut the buttonhole in a position removed from the stitch-forming mechanism, means for shifting the workclamp from stitching position to buttonhole cutting position, a threadand cord-cutter below the work-clamp, and means for lifting the work-clamp in buttonhole cutting position for the operation of the threadand cordcutter.

18. In a sewing machine, stitch-forming mechanism including a needle, a needlethroat member, a work-clamp occupying a position spaced laterally of the needle-path from the needle-throat member at the end of a sewing operation, whereby the thread to be cut extends from the last stitch to the needlethroat member substantially in contact with the under surface of the work, means for relatively separating the work-clamp and needle-throat member to cause the thread leading to the last stitch to stand at an angle to the under surface of the work, a threadcutter having a blade operating in a path transverse to the lead of the thread and close to the last stitch, said blade having a pointed extremity spaced further than the blade proped from the apex of the angle between the work and thread.

19. In a sewing machine, stitch-forming mechanism including a needle, a work-clamp, c1amp-closing means, a needle-throat member, means for relatively separating the needle-throat member and closed work-clamp transversely of the plane of the work to draw out a length of thread from the needle-throat member and separate such thread from the under surface of the work preparatory to a thread-severing operation, and means for entering the space between the separated thread and work and for severing such thread.

20. In a sewing machine, stitch-forming mechanism including a needle, a work-clamp, clamp-closing means, a needle-throat member, means for relatively separating the needlethroat member and closed work-clamp in directions laterally of the needle and transversely of the plane of the work to draw out a length of thread from the needle-throat mem her and separate such thread from the under surface of the work preparatory to a threadsevering operation, and means for severing such thread while it is separated from the work.

In testimony whereof, I have signed my name to this specification.

EDWARD B. ALLEN.

eee'rieieaee ea eeaaeetieh.

Patent Ne. 1,867,129. lieiy 12, 1932 EDWARD B. ALLEN.

It is hereby certified that errer appears in the px'iatesi speeiiieetien of the above numbered patent requiring cerreetien as ieliews: Page 3, iiee 53, for the term "x-y" read x-y; page 4, line 162, claim 14, fer "Were-flame" head WOIkclamp; page 5, line 37, claim 19, after werkwiaaiw insert the weeds in directiens iateraiiy oi the needle and; and that the said Lettete Patent sheuld be read with these eerrectiens therein that the same may eoniea'm te the reeerd of the case in the Patent Ofiiee.

Signed and sealed this 25th day ei Qcteher, A. I 3932.

M. E. hieere, (Seal) Acting iemmissiener ei Patents. 

